Cupric sulfate reduction

Colorimetric Methods. Numerous colorimetric methods exist for the quantitative determination of carbohydrates as a group (8). Among the most popular of these is the phenol—sulfuric acid method of Dubois (9), which rehes on the color formed when a carbohydrate reacts with phenol in the presence of hot sulfuric acid. The test is sensitive for virtually all classes of carbohydrates. Colorimetric methods are usually employed when a very small concentration of carbohydrate is present, and are often used in clinical situations. The Somogyi method, of which there are many variations, rehes on the reduction of cupric sulfate to cuprous oxide and is appHcable to reducing sugars. 

Triazolo[4,5-/i]quinoline 143 and triazolo[4,5-/i]quinoline-5-arsonic acid 144 were isolated from mother liquors after reduction and bis-diazotization of 5,7-dinitro-8-(4-toluenesulfone)aminoquinoline in the presence of cupric sulfate with trisodium arsenite (32JCS2196). 

The BCA method is simpler than the Lowry method and relies on the same redox reaction. The target protein is treated with alkaline cupric sulfate in the presence of tartrate, which results in the reduction of the cupric ion to cuprous by the protein. The cuprous ion is then treated with bicichoninic acid (BCA) and two... 

The action of an active intermediate oxidation product would explain another feature of the reaction. The reduction of silver ions by hydrazine is extremely sensitive to the presence of small amounts of copper. For example, a solution containing a mixture of silver nitrate, sodium sulfite and hydrazine which normally showed no sign of reduced silver for several minutes underwent almost immediate reaction when merely stirred with a clean copper rod. In the presence of gum arabic as stabilizer, streamers of colloidal silver passed out from the copper surface. Similarly, the addition of small amounts of cupric sulfate to a hydrazine solution eliminated the induction period of the reaction with silver chloride. 

Cupric sulfate exerts an effect on the silver chloride-hydroxylamine reaction similar in kind to that which it exerts on the hydrazine reaction, but in a smaller degree. If sufficient cupric sulfate is added to the hydroxylamine solution, the character of the reduction of silver chloride shifts towards that shown by the hydrazine reaction, e.g., the effect of gelatin becomes less pronounced, a minimum rate at a small gelatin addition is not obtained, and significant amounts of colloidal silver appear in the solution. 

The oxidation of methane was very slow under the experimental conditions employed The slowest rates are those with anhydrite as oxidant. Because the ratio of the rate constants, a, is dependent upon the oxidant, it is difficult to estimate the carbon isotope selectivity during sulfate reduction at temperatures relevant to TSR in sour gas occurrences. However, the effects are substantial with the cupric oxide-manganese dioxide and hematite-anhydrite trends in Figure 2 giving extrapolated a-values of about 1.02 and 1.04 respectively at 200°C. 

Metals, Metallic Oxides, and Salts. In an effort to facilitate the reduction of diazonium salts by ethanol, a number of metals, oxides, and salts are added to the reaction mixture. Finely divided cop-per, 2 - 37 68- 66- 67 cuprous oxide,6 -44- - f and cupric sulfate °-70 are often employed. 

The hydrazines usually are converted to hydrocarbons by treatment with hot, aqueous cupric sulfate, ferric chloride, or potassium chromate.7- uo 1Ui 116 113 Although hydrazines often are isolated from reduction mixtures as hydrochlorides, it is advisable to convert them to the free bases before carrying out the oxidation if this is not done, a chlorine atom may replace the hydrazine group.117 118< 119 Phenylhydrazine hydrochloride is converted to chlorobenzene in 86% yield when treated with a solution of cupric sulfate containing hydrochloric add.118... 

C. Preparation of the reducing agent. One hundred and twenty-five grams (0.5 mole) of cupric sulfate pentahydrate is dissolved in 500 ml. of water contained in a 3-1. three-necked flask equipped with a mechanical stirrer, and then 210 ml. of concentrated ammonium hydroxide (sp. gr. 0.90) is added with stirring. The solution is cooled to 10°. A solution of 40 g. (0.575 mole) of hydroxylamine hydrochloride in 140 ml. of water is prepared and also cooled to 10°. To the hydroxylamine hydrochloride solution there is added 95 ml. of 6 A sodium hydroxide solution, and if not entirely clear, it is filtered by suction. This hydroxylamine solution is immediately added to the ammoniacal cupric sulfate solution with stirring. Reduction occurs at once with the evolution of nitrogen, and the solution becomes pale blue. If this solution is not used at once, it should be protected from the air. 

The position of inosite in this series is based entirely upon its chemical composition, as it does not imssess the other characteristics of the group. It does not enter directly into alcoholic fermentation, although ui>on contact with putrefying animal matters it produces lactic and butyric acids when boiled with barium or potassium hydroxid, it is not oven colored in the presence of inosite, potash precipitates with cupric sulfate solution, the precipitate being redissolved in an excess of potash but no reduction takes place upon boiling the blue solution. 

Hydrazine cupric sulfate/hydrogen peroxide Cyclic alcohols from ethyleneketones Reductive transannular ring closure... 

It is an experimental fact that in DanieU s galvanic cell (see Chap. 2), the reaction of oxidation of the zinc [reaction (13.2)] takes place at the surface of the zinc electrode dipping into the solution of zinc sulfate, while, simultaneously, the reduction of cupric ions according to (13.3) takes place at the surface of the copper electrode dipping into the solution of cupric sulfate. The zinc and copper wires are the electrodes. The two independent half-reactions (13.2) and (13.3) describe the real chemical changes onto both electrodes. 

C) Reduction of Cupric Ion (Fehling s Reaction). To 4 ml of Fehling s solution (made by mixing equal amounts of copper sulfate solution and a solution of sodium hydroxide containing sodium potassium tartrate ) add a drop of the compound to be tested, and warm. If no change occurs immediately, heat to boiling and set aside. Compare the action of acetaldehyde and acetone or benzal-dehyde and acetophenone. 

Single phase cuprous oxide (14 nm) was prepared by °Co gamma irradiation of deoxygenated aqueous solutions containing copper sulfate, propan-2-ol, surfactant sodium dodecyl sulfate, and acetate buffer at pH 4-4.5 (Zhu et al. 1994). In the absence of buffer (pH 3-3.5), mixture of copper and cuprous oxide was observed. Most probably, three competitive reactions occur radiation reduction (Equations (4.6) and (4.8)), dismntation of cuprous ions (Equation 4.9), and the formation of cuprous hydroxide, which decomposes to cuprous oxide (Equation 4.10). In buffered solutions, the reduction and dismntation of cnprons ions are completely suppressed. Since cuprous hydroxide is very unstable, it decomposes rapidly to cnprous oxide immediately after its formation. On the other hand, the precipitate of cupric hydroxide Cu(OH)2 forms in the solution of pH >5. 

Anunonium persulfate solution, normally made up at 20 percent, is acidic. Hydrolysis reactions and etchant use cause a reduction of the pH from 4 to 2. The persulfate concentration is lowered, and hydrated cupric ammonium sulfate [CUSO4 (NH4)2S04 6H2O] is formed. This precipitate may interfere with etching. 

Spent Baths. Certain spent baths can be bled into the ion exchange system.These typically inclnde the copper sulfate electroplating dragout, acid cleaners, predips, microetch and rinses, rinses following cupric chloride and ammoniacal etchants, and copper waste from electrowinning after reduction to 1.0 ppm or less. 

The formation of (II) provides a quite selective spot test for palladium. Gold must be removed prior to the test because it will cause the development of a deep ruby red in the spot plate test and a diffused violet spot on the paper, apparently due to the reduction of the gold ions to the colloidal metal. Interference may also arise from 0s04 , Os+, Ru+, and RuCle ions because they have distinct self-colors. Mercurous ion causes partial interference by the reduction of part of the palladium to the elementary state, but a positive response can still be seen. It is possible to detect I part of palladium in the presence of 200 parts of platinum or 100 parts of rhodium. Less favorable ratios should be avoided because of the color of these salts. No interference is caused by mercuric and iridic chloride, but free ammonia, ammonium ions, stannous, cyanide, thiocyanate, fluoride, oxalate, and tetraborate ions do interfere. Lead, silver, ferrous, ferric, stannic, cobaltous, nickel, cupric, nitrite, sulfate, chloride, and bromide ions do not interfere. 

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